Rail car couplers conventionally consist of a body having an open recess defined therein for receiving the knuckle head of the coupler of the adjacent car. A knuckle pivotally mounted upon the coupler body is pivotal between a closed position which couples adjacent cars, or is pivotal to an open condition releasing the head of the knuckle of the adjacent coupler.
Pivoting of the knuckle is controlled by a coupling pin usually vertically displaceable within the coupler body. At one position the coupler pin engages a portion of the knuckle structure to prevent pivoting and lock the knuckle in its closed coupling position. In the other condition the coupling pin is displaced to clear the knuckle and permit pivoting thereof to an open uncoupling position.
The position of the coupling pin is operated by a lever readily accessible to the brakeman, or others standing adjacent the rail car coupling. By raising or lowering the operating lever the knuckle is "locked" or "unlocked", and as the coupling pin operating lever is not normally secured by a padlock, or other security device, the coupling pin could be pulled to its unlocked condition during train movement. Also, due to vibration, humping, or bumps, the actuating lever, or coupling pin, may inadvertently be sufficiently jarred to release the coupling knuckle creating a serious safety problem when the rail cars are in motion.
It is an object of the invention to provide a safety interlock for rail car couplers wherein apparatus is utilized which prevents the coupler from being uncoupled as long as the rail car air system is pressurized.
A further object of the invention is to provide a rail car coupler safety device which positively prevents the coupling pin from being moved from a locking to an unlocking position while the rail car compressed air system is pressurized.
An additional object of the invention is to provide a rail car coupler interlock employing a detent operated by compressed air wherein the detent engages the coupling pin and prevents inadvertent coupling pin displacement.
In the practice of the invention the safety interlock is utilized with a conventional rail car coupler having a body which includes a recess for receiving the pivoted knuckle of the coupler of the adjacent car. Each coupler body includes a pivotal knuckle capable of pivoting between open and closed conditions, and pivoting of the knuckle is controlled by a displaceable coupling pin which is actuated by a manually operable lifting bar. The interlock is mounted in the body and selectively engages the coupling pin to prevent its movement from a knuckle locking position to an unlocking position.
The interlock comprises a displaceable detent operated by an expansible motor selectively communicating with the rail car compressed air system, such as used for braking purposes. The expansible motor is connected to the compressed air system by a manually operable valve, which will bleed off compressed air when closed, and movement of the detent to the retracted or unlocked position is under the influence of a compression spring.
As the detent will engage the coupling pin at all times when the rail car compressed air system is pressurized the detent will prevent the coupling pin from being moved to an unlocking condition while the rail car is in use. Thus, rail cars utilizing the invention, while in use, cannot be purposefully or accidentally uncoupled. The apparatus of the invention is relatively inexpensive to manufacture and install, and existing couplers can be retrofitted with the apparatus of the invention.